Ok I just finished my build from PSA I have a ptac lower and pa10 18" ss upper. My issue now is that when I took her to the range when I would run the bolt the round would seat but bolt would be about 1/4 to 1/2" out of battery and not attached to the round... I am thinking it might be a problem with a not strong enough buffer or buffer spring. I have a PSR stock instaled but lower parts kit from psa came with a carbine stock kit... do I need a new budder and spring or is it something else?